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Home >> Volvo >> 2006 >> C70 L5-2.5L Turbo VIN 68 B5254T3 >> Repair and Diagnosis >> Accessories and Optional Equipment >> Antitheft and Alarm Systems >> Keyless Entry >> Description and Operation >> Keyless Vehicle Module (KVM) >> System Overview

System Overview






System overview

General




The keyless entry system allows the vehicle to be opened without inserting a key in the lock or pressing a button on the remote control. The system also allows the engine to be started without the ignition key in the ignition switch. The function is checked by the keyless vehicle module (KVM). The control module is under the left front seat. In order to be able to fulfill its tasks, the keyless vehicle module (KVM) is connected to a number of other units such as:
- Antennas in the external door handles
- Antennas in the passenger compartment and cargo compartment
- An antenna in the rear bumper
- Quick lock motors in the lock units in the side doors
- The remote keyless entry (RKE) receiver receives a signal from the key
- The switch in the clutch pedal (manual transmissions) or a signal from the brake pedal switch via the central electronic module (CEM) (automatic transmissions)
- Key-in switch.
- Switch in door handle and locking button on handle (2006-)
The keyless vehicle module (KVM) is part of the immobilizer system. It communicates with both the central electronic module (CEM) and driver information module (DIM) via the LS-CAN. For further information, see Design and Function, Immobilizer/Start inhibition.
The external antennas are in the door handles and rear bumper. If a door handle is pulled out, a switch closes. This wakes the system and activates the antennas in the handles on the side on which the handles was pulled out. If there is a valid key within a radius of approximately 1.5 meters of the handles, that door will open and one or more doors will be unlocked. The doors which unlock depend on the system settings. The vehicle can also be unlocked if the trunk lid/tailgate handle is affected.
There are additional antennas inside the vehicle which are activated during start attempts. These allow the control module to check for a valid key in the vehicle. If there is, the vehicle can be started using the starter button on the dashboard.
There are quick locks in the lock units in the doors. These increase the response time of the system. The quick locks are mechanically connected to the standard lock mechanism. The quick locks can open the door themselves. The time taken from the handle being pulled out to the door opening is reduced. The keyless vehicle module (KVM) checks the key, and then opens the first door itself. This saves communication time over the controller area network (CAN) which is used otherwise by the central electronic module (CEM) to check the central locking.
The remote keyless entry (RKE) receives signals transmitted by the key. These are sent on to the keyless vehicle module (KVM).
A switch at the brake pedal (vehicles with automatic transmissions) or at the clutch pedal (vehicles with manual transmissions) informs the system that the vehicle is about to be started. When the switch closes, the keyless vehicle module (KVM) starts scanning for a valid key.
There are diagnostics for the system. Any diagnostic trouble codes (DTCs) can be read off using VIDA.

Note! There have been some cases of system malfunctions when communication between the Keyless Vehicle Module (KVM) and the ignition switch has experienced interference for various reasons. These malfunctions are not due to electrical faults and will not generate a diagnostic trouble code.

1. If the ignition key is held in the same hand that is used to turn the starter, the ignition key may not be identified correctly. This will display an error message in the Driver Information Module (DIM). The vehicle will not start either. The vehicle will start, however, if the starter is turned to 0 and a new starting attempt is made. The fault will not generate a diagnostic trouble code. This fault is rare.
2. If a button on the remote control is pressed when the Keyless Vehicle Module (KVM) attempts to read the identity of the ignition key, the reading will fail. This is because the ignition key cannot not transmit and receive data at the same time (pressing a button on the remote control will mean the ignition key is engaged in transmitting a "normal" remote control command). This fault could occur if the key is kept in a pocket or bag and a button is pressed by mistake.
3. Due to increased external radiation, for example from TV/radio transmitters and mobile telephones, the signal from the remote control can on rare occasions be jammed. This is a rare fault but it can occur, especially in particular places where different external signals can impair transmitting and reception conditions. This is not only associated with keyless systems but can also affect different types of wireless communication.

Signals
The table below summarizes the input signals to and output signals from the keyless vehicle module (KVM). The signal types are divided into directly connected signals, serial communication and controller area network (CAN) communication. The illustration below displays the same information with the Volvo component designations.










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